Teens can go and we saw lots there. I was there so I do not know if there were any who did not go. It is cute and you can watch the younger kids. They just come to your table and take their picture with you. As for adults no kids, there were many on the ship so it is hard to tell if their children were not with them, but they were there in the dining room having a good time.
You don't have to do anything silly with the characters, you can also say no thanks to the pictures if you like. We enjoyed but our DS6 was the perfect age for it.